Q&A - PSLE Math

[yongjianrong]

w13158:

cimman:

yes, nowadays, maths is not so simple. Not only does the students have to contend with mathematical concepts, they have to contend with the ambiguity of the questions. They should at least have stated some assumptions in the questions, like, Sally reads everyday. But no, they leave it out, so that students are further confused. So many questions of these nature in the exams.

I agreed that this question is not clearly set. The best answer should be 525/30=17.5. Unless it is stated that the book must be read everyday without break, that is, taking into account idle time (day). If that condition is in, then another condition need to be there, on which day was the book received. If Sally received on Mon-the answer is 26 days, on Tue/Wed/Sun- the answer is 25 days, on Thu/Fri/Sat- 24 days. Perhaps student can bring this up to their teacher and forward their concern to the examination board.

The question is asking for the LEAST number of days required, hence the answer should be '24 days'. Although the book can also take 25 or 26 days to be completed, but 24 days is the least number of days required.

[shurley197323]

Pls help. Ali has some 50cents coins and Martin has some $1 coins. ali has 49 more coins than Martin but has $4.50 less than him. How much money do they have althogether?

[tianzhu]

shurley197323:

Pls help. Ali has some 50cents coins and Martin has some $1 coins. ali has 49 more coins than Martin but has $4.50 less than him. How much money do they have althogether?

Hi

There is a similar type of question on page 280 of this thread.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=69&t=280&hilit=pretend+pretend+lah&start=2790

Box A contains 50 cent coins and Box B contains $1 coins.Box A contains 17 more coins than Box B.The amount of money in Box A is $15.50 less than in Box B.Find the total amount of money in the boxes

For your question,assume or pretend that Martin had the same number of coins as Ali.

49*1 ------ 49
49 + 4.5 ------- 53.5

Difference between $1 and 50 cents -------50 cents

5350/50 ------107 50 cents coins

107*0.5 ----- 53.5

Hence, 58 $1 coins

58 + 53.5 -------- 111.50

Best wishes

[shurley197323]

Thanks. Tianzhu

[hypergatak]

hi


Appreciate your input to the following question:-
1/1x2 + 1/2x3 +1/3x4 +…1/2009x2010 +1/2010x2011.

[lizawa]

hypergatak:

hi


Appreciate your input to the following question:-
1/1x2 + 1/2x3 +1/3x4 +...........................................1/2009x2010 +1/2010x2011.

You need to see the pattern that
1/1x2 = 1/1 - 1/2
1/2x3 = 1/2 - 1/3
1/3x4 = 1/3 - 1/4 etc

So expand the question, you get
1/1 - 1/2 + 1/2 -1/3+1/3 -1/4.......+ 1/2010 - 1/2011
All terms in the centre are eliminated except first and last
= 1/1 - 1/2011 = 2010/2011

[hypergatak]

Thanks for your help.

[speedmaths.012624com]

hypergatak:

hi


Appreciate your input to the following question:-
1/1x2 + 1/2x3 +1/3x4 +...........................................1/2009x2010 +1/2010x2011.

P6 pupils (2012) can learn to answer such questions in our PSLE Maths camps.

http://www.kiasuparents.com/kiasu/forum/viewtopic.php?f=43&t=25433


Speedmaths.com

[Chan09]

Some help on this:

Mr Tan saves 15% of his salary. His savings increased by $18 when his salary increases by 5%. what is his salary before the increase?
Ans:$2400

[lizawa]

Chan09:

Some help on this:

Mr Tan saves 15% of his salary. His savings increased by $18 when his salary increases by 5%. what is his salary before the increase?
Ans:$2400

Before :
Savings : 15%; salary : 100%
After :
Salary : 105%
savings -> 15% x 105 = 15.75%
0.75% -> 18
(salary before increase) 100% -> 18/0.75 x 100 = 2400